Histamine-2 receptor antagonists (H2 blockers) are widely used to treat gastric ulcers and the hypersecretory syndrome. These drugs are considered to have very few side effects. We describe a patient with erythema multiforme that led to serious generalized exfoliative erythroderma caused by the H2 blockers cimetidine and famotidine.

In a clinic, a 68-year-old woman had received the calcium-channel blocker efonidipine for hypertension and cimetidine for reflux esophagitis and suspected gallstones. She was admitted to our hospital for detection and treatment of gallstones. Erythema multiforme lesions were noted on the extremities and abdomen. The calcium-channel blocker manidipine and famotidine were initially administered for 4 days. After dermatologic examination to determine causative drugs, famotidine was terminated. On skin biopsy, the eruptions were found to be histologically exudative erythema, but serious generalized exfoliative erythroderma was apparent. Results of tests for drug lymphocyte stimulation were negative. With the patient's consent, cimetidine was administered after a washout period. Erythema multiforme eruptions similar to the initial eruptions subsequently appeared; itching also developed. After a second washout period, famotidine was given again; similar eruptions with itching developed. The calcium-channel blocker manidipine was not found to be a causative agent.